What is the idiom that expresses "What is Wuyun"?

The idiom expressing "what is cloudless" is cloudless, pinyin: wàn lǐ wú yún, meaning: a clear blue sky without a trace of cloud. Describes sunny weather.

Sentence:

1. The beautiful kite dances in the cloudless sky.

2. On the night of the Mid-Autumn Festival, the bright moon was in the sky and there were no clouds in the sky. The family sat together and tasted the sweet mooncakes, feeling indescribably happy.

3. On the day we traveled to Qingfeng Mountain, the sky was cloudless and it was a crisp autumn day. Everyone had a great time.

4. The weather is sunny and cloudless today.

5. The sun is so hot today that everything seems to be roasted. There are no clouds in the sky and green grass on the ground. This is a great time for spring outings.